Several immune diseases seriously compromise life quality of patients and cause important deficit in general body functions. One common autoimmune disease is the Insulin Deficient Diabetes Mellitus (namely IDDM) which arises during childhood and often correlates with autoimmune response versus pancreatic islets. Transplantation is the best treatment for this kind of disease, but is possible only in presence of a compatible allotype and also in this case the possibility to have a rejection is quite high. Immune suppression and other similar approaches have been optimized to bypass this problem. For this purpose, since few years the role of dendritic cells in autoimmunity control has been investigated. In particular, when dendritic cells were modified by inserting IL10 gene and injected into kidney mouse model, T lymphocyte proliferation was inhibited and apoptosis was induced, glucose plasma levels were downregulated and returned to normal value. In general, IL10 transfection generated a favourable tolerance of islet graft and prolonged survival of recipients by inhibiting T cells proliferation. Other studies must be done about the role of IL10 in autoimmunity and signalling pathways involved in this process. The final goal is totally decreasing the likelihood to have rejection after transplantation and making possible this treatment also in the case of not complete compatibility between donor and host.